Watchdog is a daemon that checks if your system is still working. If
programs in user space are not longer executed it will reboot the system.
However, it will not always work.

From the kernel:

>	Watchdog Timer Interfaces For The Linux Operating System
>
>		Alan Cox <alan@lxorguk.ukuu.org.uk>
>
>	    Custom Linux Driver And Program Development
>
>[...]
>
>All four interfaces provide /dev/watchdog, which when open must be written
>to within a minute or the machine will reboot. Each write delays the reboot
>time another minute. In the case of the software watchdog the ability to 
>reboot will depend on the state of the machines and interrupts. The hardware
>boards physically pull the machine down off their own onboard timers and
>will reboot from almost anything.

This tool proved very useful for me, because I always run the latest kernel
and the latest libc release, but rely on the machine to be up and running
for email.

Note, that you have to enable the software watchdog driver in your kernel
for the program to be able to reboot the system. In particular you have to
use a fairly recent kernel, because the driver is pretty new (about 1.3.52+).
Also make sure you don't compile watchdog with a differemt timer margin than
the driver.

Michael
meskes@informatik.rwth-aachen.de

